This is another of my favorite topics. Most of us learn note values as an arithmetic function having nothing whatsoever to do with sound or with the perception of tone. Students get the idea that they must first "get it right" and only then add in "feeling." But by the time one has mastered the arithmetic the critical germ of feeling has usually been obscured.
As one brilliant nine-year-old once put it: " It is really hard to count and play at the same time."
Note values should never be taught as absolutes for to do is to rob them of their infinitely expressive capacity.
For example: Today a young adult student was sight-reading a Bartok piece based on a Slovak folk tune. Just playing the melody she was distorting the note values quite a bit. Rather than correct her outright I had her comment on each successive tone: Did she like it or not? Did she want to go on to the next tone or not? By the time she had read through the melody she noted that one measure in which there are four long repeated F-sharps sounded like a church bell.
Wow!
She heard it. That very strong response galvanized the entire experience for her and the values took on meaning.